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Release 4.14 drivers/pwm/pwm-bcm-kona.c

Directory: drivers/pwm
/*
 * Copyright (C) 2014 Broadcom Corporation
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation version 2.
 *
 * This program is distributed "as is" WITHOUT ANY WARRANTY of any
 * kind, whether express or implied; without even the implied warranty
 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/io.h>
#include <linux/ioport.h>
#include <linux/math64.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/pwm.h>
#include <linux/slab.h>
#include <linux/types.h>

/*
 * The Kona PWM has some unusual characteristics.  Here are the main points.
 *
 * 1) There is no disable bit and the hardware docs advise programming a zero
 *    duty to achieve output equivalent to that of a normal disable operation.
 *
 * 2) Changes to prescale, duty, period, and polarity do not take effect until
 *    a subsequent rising edge of the trigger bit.
 *
 * 3) If the smooth bit and trigger bit are both low, the output is a constant
 *    high signal.  Otherwise, the earlier waveform continues to be output.
 *
 * 4) If the smooth bit is set on the rising edge of the trigger bit, output
 *    will transition to the new settings on a period boundary (which could be
 *    seconds away).  If the smooth bit is clear, new settings will be applied
 *    as soon as possible (the hardware always has a 400ns delay).
 *
 * 5) When the external clock that feeds the PWM is disabled, output is pegged
 *    high or low depending on its state at that exact instant.
 */


#define PWM_CONTROL_OFFSET			(0x00000000)

#define PWM_CONTROL_SMOOTH_SHIFT(chan)		(24 + (chan))

#define PWM_CONTROL_TYPE_SHIFT(chan)		(16 + (chan))

#define PWM_CONTROL_POLARITY_SHIFT(chan)	(8 + (chan))

#define PWM_CONTROL_TRIGGER_SHIFT(chan)		(chan)


#define PRESCALE_OFFSET				(0x00000004)

#define PRESCALE_SHIFT(chan)			((chan) << 2)

#define PRESCALE_MASK(chan)			(0x7 << PRESCALE_SHIFT(chan))

#define PRESCALE_MIN				(0x00000000)

#define PRESCALE_MAX				(0x00000007)


#define PERIOD_COUNT_OFFSET(chan)		(0x00000008 + ((chan) << 3))

#define PERIOD_COUNT_MIN			(0x00000002)

#define PERIOD_COUNT_MAX			(0x00ffffff)


#define DUTY_CYCLE_HIGH_OFFSET(chan)		(0x0000000c + ((chan) << 3))

#define DUTY_CYCLE_HIGH_MIN			(0x00000000)

#define DUTY_CYCLE_HIGH_MAX			(0x00ffffff)


struct kona_pwmc {
	
struct pwm_chip chip;
	
void __iomem *base;
	
struct clk *clk;
};


static inline struct kona_pwmc *to_kona_pwmc(struct pwm_chip *_chip) { return container_of(_chip, struct kona_pwmc, chip); }

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Tim Kryger25100.00%1100.00%
Total25100.00%1100.00%

/* * Clear trigger bit but set smooth bit to maintain old output. */
static void kona_pwmc_prepare_for_settings(struct kona_pwmc *kp, unsigned int chan) { unsigned int value = readl(kp->base + PWM_CONTROL_OFFSET); value |= 1 << PWM_CONTROL_SMOOTH_SHIFT(chan); value &= ~(1 << PWM_CONTROL_TRIGGER_SHIFT(chan)); writel(value, kp->base + PWM_CONTROL_OFFSET); /* * There must be a min 400ns delay between clearing trigger and setting * it. Failing to do this may result in no PWM signal. */ ndelay(400); }

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Tim Kryger5887.88%150.00%
Jonathan Richardson812.12%150.00%
Total66100.00%2100.00%


static void kona_pwmc_apply_settings(struct kona_pwmc *kp, unsigned int chan) { unsigned int value = readl(kp->base + PWM_CONTROL_OFFSET); /* Set trigger bit and clear smooth bit to apply new settings */ value &= ~(1 << PWM_CONTROL_SMOOTH_SHIFT(chan)); value |= 1 << PWM_CONTROL_TRIGGER_SHIFT(chan); writel(value, kp->base + PWM_CONTROL_OFFSET); /* Trigger bit must be held high for at least 400 ns. */ ndelay(400); }

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Tim Kryger3450.75%150.00%
Jonathan Richardson3349.25%150.00%
Total67100.00%2100.00%


static int kona_pwmc_config(struct pwm_chip *chip, struct pwm_device *pwm, int duty_ns, int period_ns) { struct kona_pwmc *kp = to_kona_pwmc(chip); u64 val, div, rate; unsigned long prescale = PRESCALE_MIN, pc, dc; unsigned int value, chan = pwm->hwpwm; /* * Find period count, duty count and prescale to suit duty_ns and * period_ns. This is done according to formulas described below: * * period_ns = 10^9 * (PRESCALE + 1) * PC / PWM_CLK_RATE * duty_ns = 10^9 * (PRESCALE + 1) * DC / PWM_CLK_RATE * * PC = (PWM_CLK_RATE * period_ns) / (10^9 * (PRESCALE + 1)) * DC = (PWM_CLK_RATE * duty_ns) / (10^9 * (PRESCALE + 1)) */ rate = clk_get_rate(kp->clk); while (1) { div = 1000000000; div *= 1 + prescale; val = rate * period_ns; pc = div64_u64(val, div); val = rate * duty_ns; dc = div64_u64(val, div); /* If duty_ns or period_ns are not achievable then return */ if (pc < PERIOD_COUNT_MIN || dc < DUTY_CYCLE_HIGH_MIN) return -EINVAL; /* If pc and dc are in bounds, the calculation is done */ if (pc <= PERIOD_COUNT_MAX && dc <= DUTY_CYCLE_HIGH_MAX) break; /* Otherwise, increase prescale and recalculate pc and dc */ if (++prescale > PRESCALE_MAX) return -EINVAL; } /* * Don't apply settings if disabled. The period and duty cycle are * always calculated above to ensure the new values are * validated immediately instead of on enable. */ if (pwm_is_enabled(pwm)) { kona_pwmc_prepare_for_settings(kp, chan); value = readl(kp->base + PRESCALE_OFFSET); value &= ~PRESCALE_MASK(chan); value |= prescale << PRESCALE_SHIFT(chan); writel(value, kp->base + PRESCALE_OFFSET); writel(pc, kp->base + PERIOD_COUNT_OFFSET(chan)); writel(dc, kp->base + DUTY_CYCLE_HIGH_OFFSET(chan)); kona_pwmc_apply_settings(kp, chan); } return 0; }

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Tim Kryger23996.37%133.33%
Jonathan Richardson83.23%133.33%
Boris Brezillon10.40%133.33%
Total248100.00%3100.00%


static int kona_pwmc_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm, enum pwm_polarity polarity) { struct kona_pwmc *kp = to_kona_pwmc(chip); unsigned int chan = pwm->hwpwm; unsigned int value; int ret; ret = clk_prepare_enable(kp->clk); if (ret < 0) { dev_err(chip->dev, "failed to enable clock: %d\n", ret); return ret; } kona_pwmc_prepare_for_settings(kp, chan); value = readl(kp->base + PWM_CONTROL_OFFSET); if (polarity == PWM_POLARITY_NORMAL) value |= 1 << PWM_CONTROL_POLARITY_SHIFT(chan); else value &= ~(1 << PWM_CONTROL_POLARITY_SHIFT(chan)); writel(value, kp->base + PWM_CONTROL_OFFSET); kona_pwmc_apply_settings(kp, chan); clk_disable_unprepare(kp->clk); return 0; }

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Tim Kryger14395.33%150.00%
Jonathan Richardson74.67%150.00%
Total150100.00%2100.00%


static int kona_pwmc_enable(struct pwm_chip *chip, struct pwm_device *pwm) { struct kona_pwmc *kp = to_kona_pwmc(chip); int ret; ret = clk_prepare_enable(kp->clk); if (ret < 0) { dev_err(chip->dev, "failed to enable clock: %d\n", ret); return ret; } ret = kona_pwmc_config(chip, pwm, pwm_get_duty_cycle(pwm), pwm_get_period(pwm)); if (ret < 0) { clk_disable_unprepare(kp->clk); return ret; } return 0; }

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Tim Kryger9494.00%150.00%
Boris Brezillon66.00%150.00%
Total100100.00%2100.00%


static void kona_pwmc_disable(struct pwm_chip *chip, struct pwm_device *pwm) { struct kona_pwmc *kp = to_kona_pwmc(chip); unsigned int chan = pwm->hwpwm; unsigned int value; kona_pwmc_prepare_for_settings(kp, chan); /* Simulate a disable by configuring for zero duty */ writel(0, kp->base + DUTY_CYCLE_HIGH_OFFSET(chan)); writel(0, kp->base + PERIOD_COUNT_OFFSET(chan)); /* Set prescale to 0 for this channel */ value = readl(kp->base + PRESCALE_OFFSET); value &= ~PRESCALE_MASK(chan); writel(value, kp->base + PRESCALE_OFFSET); kona_pwmc_apply_settings(kp, chan); clk_disable_unprepare(kp->clk); }

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Tim Kryger6453.78%150.00%
Jonathan Richardson5546.22%150.00%
Total119100.00%2100.00%

static const struct pwm_ops kona_pwm_ops = { .config = kona_pwmc_config, .set_polarity = kona_pwmc_set_polarity, .enable = kona_pwmc_enable, .disable = kona_pwmc_disable, .owner = THIS_MODULE, };
static int kona_pwmc_probe(struct platform_device *pdev) { struct kona_pwmc *kp; struct resource *res; unsigned int chan; unsigned int value = 0; int ret = 0; kp = devm_kzalloc(&pdev->dev, sizeof(*kp), GFP_KERNEL); if (kp == NULL) return -ENOMEM; platform_set_drvdata(pdev, kp); kp->chip.dev = &pdev->dev; kp->chip.ops = &kona_pwm_ops; kp->chip.base = -1; kp->chip.npwm = 6; kp->chip.of_xlate = of_pwm_xlate_with_flags; kp->chip.of_pwm_n_cells = 3; res = platform_get_resource(pdev, IORESOURCE_MEM, 0); kp->base = devm_ioremap_resource(&pdev->dev, res); if (IS_ERR(kp->base)) return PTR_ERR(kp->base); kp->clk = devm_clk_get(&pdev->dev, NULL); if (IS_ERR(kp->clk)) { dev_err(&pdev->dev, "failed to get clock: %ld\n", PTR_ERR(kp->clk)); return PTR_ERR(kp->clk); } ret = clk_prepare_enable(kp->clk); if (ret < 0) { dev_err(&pdev->dev, "failed to enable clock: %d\n", ret); return ret; } /* Set push/pull for all channels */ for (chan = 0; chan < kp->chip.npwm; chan++) value |= (1 << PWM_CONTROL_TYPE_SHIFT(chan)); writel(value, kp->base + PWM_CONTROL_OFFSET); clk_disable_unprepare(kp->clk); ret = pwmchip_add_with_polarity(&kp->chip, PWM_POLARITY_INVERSED); if (ret < 0) dev_err(&pdev->dev, "failed to add PWM chip: %d\n", ret); return ret; }

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Tim Kryger32498.78%150.00%
Arun Ramamurthy41.22%150.00%
Total328100.00%2100.00%


static int kona_pwmc_remove(struct platform_device *pdev) { struct kona_pwmc *kp = platform_get_drvdata(pdev); unsigned int chan; for (chan = 0; chan < kp->chip.npwm; chan++) if (pwm_is_enabled(&kp->chip.pwms[chan])) clk_disable_unprepare(kp->clk); return pwmchip_remove(&kp->chip); }

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Tim Kryger7298.63%150.00%
Boris Brezillon11.37%150.00%
Total73100.00%2100.00%

static const struct of_device_id bcm_kona_pwmc_dt[] = { { .compatible = "brcm,kona-pwm" }, { }, }; MODULE_DEVICE_TABLE(of, bcm_kona_pwmc_dt); static struct platform_driver kona_pwmc_driver = { .driver = { .name = "bcm-kona-pwm", .of_match_table = bcm_kona_pwmc_dt, }, .probe = kona_pwmc_probe, .remove = kona_pwmc_remove, }; module_platform_driver(kona_pwmc_driver); MODULE_AUTHOR("Broadcom Corporation <bcm-kernel-feedback-list@broadcom.com>"); MODULE_AUTHOR("Tim Kryger <tkryger@broadcom.com>"); MODULE_DESCRIPTION("Broadcom Kona PWM driver"); MODULE_LICENSE("GPL v2");

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PersonTokensPropCommitsCommitProp
Tim Kryger131391.37%120.00%
Jonathan Richardson1127.79%120.00%
Boris Brezillon80.56%240.00%
Arun Ramamurthy40.28%120.00%
Total1437100.00%5100.00%
Directory: drivers/pwm
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